sklearn的cosine_similarity余弦相似怎么用？

我想计算两个向量的余弦相似，代码如下

from sklearn.metrics.pairwise import cosine_similarity
cosine_similarity([1, 2], [2, 1])

结果出错，错误信息如下

ValueError: Expected 2D array, got 1D array instead:
array=[1. 2.].
Reshape your data either using array.reshape(-1, 1) if your data has a single feature or array.reshape(1, -1) if it contains a single sample.

怎么试都不行，头大了